Reenforced filter paper and process of making same



Nov. 25, 1930. F. w. MANNING REENFORCED FILTER PAPER AND PROCESS OF MAKING SAME Filed April 11. 1927 2 Sheets-Sheet l INVENTOR.

aw LBJ- Nov. 25, 1930. F. w. MANNING REBNFORCED FILTER PAPER AND PROCESS OF MAKING SAME 2 Sheets-Sheet 2 Filed April 11. 1927 INVENTOR.

Patented Nov. 25, 1930 UNITED STATES PATENT OFFICE FRED W. MANNING, 0F BERKELEY, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO FILTER FABRICS,'INC., OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSA- CEUSETTS REENFORCED FILTER PAPER AND PROCESS OF MAKING SAME Application filed April 11,

This invention relates to the manufacture of filter pa er and particularly pertains to an improved lter paper and process for producing the same.

Heretofore, filter papers have been manufactured much the same as other kinds of papers in that the paper is first formed on a F ourdrinier machine and then the moisture removed by passing the paper between or over squeezing and hot drying rolls. Such operations result in destruction and distortion of the pores formed in the wet paper pulp, on the Fourdrinier apron. Smooth metal surfaces crush the moist paper fibres and the hot drying cylinders shrink the fibres unevenly. Moreover, such .papers readily disintegrate especially when subjected to the passin through them of the hot fluids to be treateri and if they are strengthened in any way it is usually accomplished by running the pulp and a web of cloth together through a couch press so that the two amalgamate, which also aids in destroying the porosity of the paper.

It is therefore, the principal object of this invention to provide an improved filter paper and a process for producing the same. With this object in View the present invention contemplates the proyision of a new method in which the paper pulp is built or precipitated upon a strengthening medium by passing therethrough the fluid which conve s the pulp. The pores of the paper thus ormed are then ke t open and the portion of the conveying fl ilid remaining in the paper removed by passing treating fluids through the paper either by means of suction, or pressure, or both. This treating operation is continued until the porous structure of the paper has assumed a rigidity that can be maintained,

after which a low temperature fluid may be circulated in contact with the paper, if desired. The temperatures and ressures of the conveying and treating flui s will depend upon the materials used to make the paper and how and for what purpose the paper is required.

The paper pulp may consist of any treating .material, such as cotton linters, wood pulp,

asbestos, wool, kieselguhr, decolorizing car- 1927. Serial No. 182,926.

bon, etc., or a combination of them that can be used for filtering purposes, and they may be while being passed through a treating chamber, with other treating agents such as copper sulphate, cop r chloride, etc., or salts of other metals, or the removal of sulphur compounds, etc., contained in the fluids to be filtered, or with decolorizing agents such as fullers earth, bone char, etc., for other purification purposes. If the paper is impregnated with a solid in the treating chamber, the solid may be precipitated or deposited (these two terms being used synonymously in this specification) on the surface or in the pores of the paper sheet by means of the passage of a treating fluid such as air or steam through the sheet.

The strengthening medium may consist of any suitable substance of greater tensile strength than, the paper pulp precipitated thereupon, such as scrim,woven fabric, or threads, of any material that will permit the passing through it or between its threads, of the paper pulp conveying and treating fluids. Throughout this specification and appended claims the word fabric will be used to cover all such substances. The supporting medium for the filter sheet, which will also usually be the conveying medium, may consist of any means that will afford satisfac: tory drainage for the conveyin and treating fluids that pass through the fi ter sheet, and

the paper fibres or articles such as an endr less wire screen be t of a Fourdrinier machine, an endless wire belt passing over a suction filter, the drainage members of a suction filter drum, or even a stationary foraminous member. If there is danger of disturbance of the paper fibres by the passage of the treating fluids, a foraminous protecting medium may be placed over and may move with the paper sheet, but it should be of a mesh or texture suitable to retain the paper fibres in position without crushing them and at the same time place no restriction on the passage of the treating fluids.

The conveying fluid may be any fluid in which the paper pulp fibres can be easily disintegrated or maintained in a state of disintegration, such as Water, oil, etc., and the treating fluids, which may be used to remove traces of the conveying fluid or other treating fluids or for activation, revivification, impregnation or catalytic treatment, may consist of air, chlorine gas, carbon dioxide, saturated or superheated steam, etc., or mixture of them, and the filter sheet when treated by them may be subject to an oxidizing, neutral, or reducing atmosphere. It a liquid such as oil be used as the disintegrating and conveying fluid, it may be removed from the freshly formed filter sheet by passing through the sheet a treating fluid such as naphtha in liquid or vapor form, and traces of naphtha may be removed from the filter sheet by passing through the sheet another treating fluid such as saturated or superheated steam, after which air may be passed through to remove the steam and prevent condensation.

The invention is exemplified in the following description and one form of apparatus for carrying out the process is illustrated by way of example in the accompanying drawings in which:

Figure 1 is a sectional plan view showing the cutting plane as passing through the treating and festoon chambers immediately above the filter paper in its passage therethrough.

Figure 2 is a longitudinal sectional cleva tion through the treating and festooning chambers.

Figure 3 is an enlarged fragmentary view in longitudinal section through the filter drum end of the treating chamber.

Figure 4 is a transverse sectional view taken on line IV--IV of Figure 3 to show the relative positions of the endless wire belts.

Figure 5 is a transverse sectional view taken on line V-V of Figure 3 to show the filtrate outlets and valve connections of the filter drum.

Referring more specifically to the drawings by reference characters: The complete apparatus comprises the treating chamber 1 and the festoon chamber 2. The treating chamber incloses the filter drum 3 which is driven from a source of power not shown, endless foraminous conveying belt 4, and endless foralninous protecting belt 5, both of which are driven in the directions indicated by the arrows. The strengthening medium 6 in its passage into the treating chamber is carried between the conveying belt and its supporting rollers 7, and after passing around the filter drum is conveyed out of the treating chamber between the conveying and protecting belts. The conveying belt is driven by means of a sprocket wheel 8 Whwe teeth connect with the sprocket holes 8 in the reenforced edges 8" of the belt and is supported and tensioned at its discharge end by tension wheel 9 provided with adjusting devices 10. The protecting belt is carried on end rollers 11 and 12 and its movement is actuated by its contact with the filter sheet advanced by the conveyor belt.

As shown in Figures 3, 4, and 5 the filter drum is provided with a number of drainage compartments 13 on its circumference which are isolated from one another, and each compartment is connected by means of a drainage outlet pipe 14 to a stationary valve 15. As the filter drum rotates the submerged compartments connect with the valve port 16 having a suction outlet 17, and the compartments through which a treating fluid is passing, connect with a valve port 18 having a suction outlet 19, but the outlets for the compartments between the point at which the conveying belt leaves the drum and the point of the drums immersion, are completely cut off so as to prevent the passage of treating fluids through them. The pulp tank 20 preferably conforms to the circular form of the filter drum and has an inlet 21 for the pulp which can be agitated for suspension or disintegration purposes by agitator 22. The treating fluid, if a liquid or vapor, may enter through spray pipe 23, or if heated air, etc., may enter through inlets 23 and 23 and distributing plate 23 into the treating chamber where an oxidizing neutral or reducing atmosphere may be maintained. The treating fluid, after passing through the filter sheet as the latter is carried over the upper portion of the drum or is conveyed between the endless belts through the treating chamber, is finally carried out either through the drum and suction conduit 19, or else through vents 24, and flue 25. The passage of the treating fluids through the treating chamber may be caused by pump pressure at inlets 23, or 23* and 23 or suction means in the flue 25. Strips 26 fastened to the side walls of the treating chamber and which bear against the reenforcing edges of the conveying belt. prevent creepage between the two. As the moisture is removed from the filter sheet the temperature must be lowered, and therefore steam coils 28 are maintained at a lower temperature than coils 27. The two sets of coils are separated by division wall 29.

The reenforced filter paper on leaving the treating chamber is carried through a straight line festoon chamber without movement of the festoons in an up and down direction. This is accomplished by means of loose sticks 50 which are first conveyed up an incline by an endless chain 51 where the loops begin to form. The sticks are then transferred to an endless chain 52 which carries the festoons through the chamber and upon reaching the farther end, an endless carry down chain 53 takes the sticks from under the loops and delivers them to a drop -sticks may be fixed to one endless chain and the paper dro ped' from above into loops between the stic s and removed at the farther end of the chamber in the same way. Warm air is blown from vents not shown, in the top .of the chamber at right angles to the direction of the movement of the paper, and

recirculated in accordance with the usual practice familiar tothose versed in the art.

The operation of the apparatus thus constructed has been in part indicated in con-' As the drum revolves the drainage compartments in the lower part of the drum rise above the pulp liquid level, and are cut off from the suction conduit 17 by the valve port 16 and are then, opened to another suction conduit 19 by means of valve ort 18, upon which a suitable treating flui for washing or d ing or other purposes enters the treatin c amber through inlet 23 or 23 and disvtrfiiuting plate 23, and passes through the filter sheet thus formed and is then drawn off through the upper drainage compartments of the drum, valve tion conduit 19. If a treating fluid such as naphtha in vapor or liquid form is used to i remove traces of a conveying fluid such as oil from the filter sheet it may be sprayed on the top of the drum from supply pipe 23, in which case the treating fluid entering inlet 23 may be steam to remove traces of naphtha from the filter sheets. Coils 27 are used to highly heat the treating fluid that enters at 23- As the filter sheet leaves the drum between the endless conveyor belt and the endless protecting belt, the upper drainage compartments between the conveyor belt and the point of the drums immersion are cut oil from the suction conduit 19 by means of valve port 18 and these compartments are not again subjected to a suction pressure until after their immersion in the liquid pulp. The treating fluid such as steam enort 1B and suctering at 23 and hi hly heated by steam coils 27 then passes through the filter sheet and is carried off by vents 24 and flue 25, and with the progress of the filter sheet toward the outer end of the treating chamber, is followed by another treating fluid such as air enterin at 23" and heated by coils 28, which may he also carried off in the same'way.

The porous structure of the filter sheet by the time it has reached the exit of the treating chamber and inlet of the festoonchamber/has assumed a suflicient rigidity to withstand the ,com aratively low sure and temperature 0 the drying flui s in l'BS- I the festoon chamber which circulate around the filter sheet. by the inclined endless chain 51 at the time the filter sheet is looped, and are then transferred to endless chain 52 and finally are carried; from under the loops by endless carry down chain 53, whereupon the filter sheet is carried out of the festoon chamber over a guide roller 56 and wound upon roll 57 It will thus be seen from the foregoing description that the'speed of the conveying belt which is driven by a sprocket wheel attached to the filter drum, may be used to regulate the thickness of the filter paper built upon the stren thening medium during the time of its su mersion, and also the extent of the drying or other action by the treating fluids. Increasing the speed of the drum will decrease the length of the pulp depositing time, decrease the thickness of the aper thickness, decrease the time in cli treating fluids are passed through the filter sheet, and decrease the time for the passage of the filter sheet through the fiestoon chamber. On the other hand decreasing the speed of the drum will reverse these conditions. The extent of the treating action ma also be regulated by the'dlfierentials in pressure used to pass treating fluids throu h the filter sheet, one pressure diflerential ing supplied by the suction maintained on the upper drainaage compart- The sticks are carried up quired for the removal of mucilaginous matter from hot sugar liquors may be made from a mixture of cotton linters and wool recipitated anddried on a cotton scrim, w ile filter sheets to be used for the removal of sulphur compounds from petroleum distillates in the vapor phase, must be made to withstand very high temperatures and may be made from asbestos fibres precipitated and dried on a fine Wire fabric, and impregnated with copper salts.

It will furthermore be evident that in order to obtain maximum filtering rates and clarity of filtrate for fluids passed throu h filter sheets, the interstices between, or tie pores through the fibres and impregnating solids, must first be made and then kept open by the passage through them of suitable conveying and treating fluids until their porous structure has assumed suflicient rigidity towithstand the further conditions to which the filter sheets may be subjected prior to use.

Having thus described my invention, what I claim is:

1. The method of making a filter sheet, which comprises recipitating a treating material upon a fabric by passing a convey- .ing fluid containing the treating material through the fabric and thereafter passing a treating fluid through the filter sheet thus formed.

2. The method of making a filter sheet,

which comprises precipitating -a treating material upon a fabric by passing a conveying fluid containing the treating material through the fabric, passing ahigh temperature treating fluid through the filter sheet thus formed and thereafter passing a lower temperature treating fluid through the said filter sheet.

3. The method of making a filter sheet, which comprises recipitating a treating material upon a fabric by passing a conveying fluid containing the treating material through the fabric, passing a high temperature treating fluid through the filter sheet thus formed, and thereafter circulating a lower temperature drying fluid on contact with the said filter sheet.

4. The method of making a filter sheet, which comprises precipitating a treating material upon a fabric by passing a conveying fluid containing. the treating material through the fabric, passing a high temperature treating fluid through the filter sheet thus formed, thereafter passing a lower temperature treating fluid through' the said filter sheet, and finally circulating a still lower temperature drying fluid in contact with the said filter sheet.

5. A filter sheet of the c ara r described consisting of a layer of reati g material precipitated on and ended to an open mesh fabric.

6. A filter sheet of the character described consisting of a mixture of fibrous and granular materials precipitated on and bonded to an open mesh fabric. K

7. A filter sheet of the character described consisting of a layer of felted fibrous mate- 'rial impregnated with a treating agent and precipitated on and bonded to an open mesh fabric.

8. A filter sheet of the character described consisting of fibrous pulp and filling material precipitated on and bonded to an open mesh fabric.

9. A filter sheet of the character described consisting of an open mesh fabric having a layer of fibrous felted material precipitated on and bonded toit in a porous and substantially uncrushed condition.

10. The method of making a filter sheet, comprising the steps of precipitating a fibrous material upon afabric by passing a conveying liquid carrying the material through the fabric and uniting the material and fabric permanently together, and passing a treating agent through the composite sheet so formed.

11. The method of making a filter sheet, comprising the steps of recipitating a fibrous material upon a fabric by passing a conveying fluid carrying the material through the fabric and uniting the material and fabric permanently together, and finishing the composite sheet so formed while maintaining said fibrous material in a porous and substantially uncrushed condition. 7

12. The method of making a filter sheet, comprising the steps of precipitating a fibrous material upon a fabric by passing a conveying fluid carrying the material through the fabric and uniting the material and fabric permanently together,-subjecting the composite sheet so formed to the action of a treating medium, and finishing the sheet while maintaining the fibrous material precipitated thereon in a porous condition.

13. The method of making a filter sheet, comprising the stepsof recipitating a fibrous material upon a fiibric by passing a conveying fluid carrying the material through the fabric and uniting the material and fabric permanently together, and finishing the sheet without crushing the material so deposited on the fabric.

14. A filter sheet of the character described comprising a layer of treating material precipitated on a previously formed flexible and pervious sheet of substantial tensile strength and cooperating with said sheet to form a flexible filter sheet.

15. A filter sheet of the character described comprising a mixture of fibrous and granular materials precipitated on and bonded to a previously formed pervious flexible sheet and cooperating with said sheet to form a flexible filter sheet.

16. A filter sheet of the character described comprising a layer of cellulose fibre precipitated on and bonded to an independent pervious and flexible sheet of 'textile material, and cooperating with them to form a perble pervious filter sheet.

17. A filter fabric comprising a mixture of cellulose and asbestos fibres precipitated on and bonded to a pervious sheet material of greater tensile strength than the said fibres and cooperating with them to form a pervious flexible sheet for filtering purposes.

18. A filter fabric comprising a mixture of cellulose and asbestos fibres precipitated on and bonded to a loosely fabricated Web of binding material of greater tensile strength than the fibres and cooperating therewith to form a pervious flexible web for filtering purposes.

19. A filter fabric comprising a mixture of cellulose and asbestos fibres and granular s01 ids precipitated on and bonded to a Web of textile material of greater tensile strength than that of said mixture and cooperating therewith to form a flexible sheet for filter- 20 ing purposes.

FRED W. MANNING.

17 A filter fabric comprising a mixture of cellulose and asbestos fibres precipitated on and bonded to a pervious sheet material of greater tensile stren h than the said fibres and cooperating wit them to form a pervious flexible sheet for filterin purposes.

18. A filter fabric comprising a mixture of cellulose and asbestos fibres precipitated on and bonded to a loosely fabricated web of binding material of greater tensile strength than the fibres and cooperating therewith to form a pervious flexible web for filtering purposes.

19. A filter fabric comprising a mixture of cellulose and asbestos fibres and granular solids precipitated on and bonded to a web of textile material of greater tensile strength than that of said mixture and cooperatmg therewith to form a flexible sheet for filtering purposes.

FRED W. MANNING.

CERTIFIGAT E OF CORRECTION.

Patent No. 1,782,784.

FRED w. MANNING.

it is hereby certified that error appears in the printed specification of the Page 4, lines 129 and 130, claim 16, for the word "perbie" read flexible: and that the said Letters above numbered patent requiring correction as follows:

Patent should he read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of February, A. D. 1931.

M. J. Moore, (Seal) Granted November 25, 1930, to

Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,782, 784. Granted November 25. I930, to

FRED W. MANNING.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as foilows: Page 4. lines 129 and 130, ciaim 16, for the word "perbie" read flexible; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of February, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

